1. Field of the Invention
The present invention relates generally to analog-to-digital converters.
2. Description of the Related Art
It has been found that processing signals differentially provides a number of advantages. For example, noise generation along a signal path is reduced by differential processing because it substantially rejects any noise that appears as common mode voltage. In addition, differential processing tends to cancel even-order signal harmonics so that signal distortion is significantly reduced.
Some signal sources, however, provide only single-ended source signals so that some sort of signal conditioning must be done to convert these signals to differential signals for further processing. In addition, there are situations which demand that source signals be processed along dc-coupled signal paths. For example, a receiver may provide signals for signal conditioning that cover a wide range of frequencies which begin at baseband.
Accurate processing of dc-coupled signals is difficult because of various effects such as the variation of component values over time and temperature. There exists a need, therefore, for accurate dc-coupled signal converters which can process single-ended signals having various voltage and current levels.